CN100593891C - Current protection control method and device for 24kV vacuum breaker - Google Patents

Abstract

The invention discloses a current protection control method for a 24kV vacuum circuit breaker, which comprises the following steps: 1) sampling is delayed in case of sudden power up to avoid inrush current when the stage line is suddenly closed; 2) a virtual value of the current in the circuit is calculated after stable operation; 3) if the virtual value does not exceed a setting value, sampling is redone; if the virtual value exceeds the setting value, whether the current in the line is inrush current, over current or short circuit is judged; if the current is inrush current, the sampling isredone and if the current is over current or short circuit, protection is carried out. A current protection control device for a 24kV vacuum circuit breaker which fulfills the current protection method comprises a power module, a single chip microcomputer, an A, C phase current transformer, an electric quantity signal input module, a dial switch status input module, a relay output module and a trip coil drive module. The method and the device of the current protection control device have accurate control and the purpose thereof is easy to be realized.

Description

Current protection control method in the 24kV vacuum circuit-breaker

Technical field

The invention belongs to the microcomputer protective relay field, relate in particular to 24kV circuit overcurrent, short circuit syllogic current protection and escape current protection control method and the device that circuit shoves.

Background technology

High speed development along with social economy and science and technology, the city load density is increasing, many inadaptabilities have appearred in 12kV distribution, and the 24kV distribution have investment low, save characteristics such as line loss, power supply capacity are strong, its social benefit and economic benefit all are very tangible.For this reason, China is just throwing huge fund at present the 24kV electrical network is being built, and wherein Jiangsu Province's area portion has been carried out the all-round construction of 24kV distribution line.Can distribution system safely, stable, operation reliably, not only be directly connected to the unobstructed of business electrical, and relate to electric power system and can move normally, therefore, when certain bar circuit is in the abnormal running state in the distribution network, line-breaker should be able to be in time, reliably with its excision, with trouble-proof further generation and expansion.In addition, when existing no-load transformer to close a floodgate in the circuit, can occur an instantaneity on the line and shove.Because it is not fault, line-breaker need not move, but its amplitude is very big, can cause the circuit situation unsuccessful or that higher level's line-breaker mistake is jumped of once closing a floodgate.Therefore, in actual motion, need line-breaker can cut off the circuit that is in overcurrent, short-circuit condition, can distinguish shoving of instantaneous appearance on overcurrent, short-circuit condition and the circuit of circuit again.

At present; line-breaker is less with the current protection control device; and conventional device has been taked based on the peak value of the electric current determination methods as setting value for the judgement of circuit overcurrent, short circuit, shoves and adds certain delay time when having taked line-breaker to close a floodgate suddenly and realize for escaping circuit.There are certain defective in overcurrent, the short-circuit condition of judging circuit like this, and higher level's line-breaker might miss jumping because of shoving when subordinate's circuit closes a floodgate suddenly.

Summary of the invention

For the problems referred to above that exist in the technical solution, the invention provides new current protection control method and the device of a kind of 24kV of being suitable for, concrete technical scheme is as follows:

A kind of current protection control method comprises step: time-delay sampling when powering on suddenly, and what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves; After stable operation, calculate current effective value; If effective value does not surpass setting value, then resampling; If effective value surpasses setting value, judge that then electric current shoves or overcurrent/short circuit in the circuit; If shove then resampling; If the protection action is then made in overcurrent/short circuit.Setting value determines that by the electric current of minitype CT 1 secondary side the setting value scope is at 5A-30A.

Current effective value is by formula in the described decision circuitry:

Draw; In the formula, the sampling number of the every power frequency period of N-; i _iThe instantaneous value of-sampling instant electric current.The desirable 5A-30A of described setting value scope.Described sampling number is 〉=20, and the sampling period is 20ms.Determining of sampling period because power frequency is 50Hz in the available circuit.

By formula:

Calculate the difference of k point place's half-wave fourier algorithm and all-wave fourier algorithm, in the formula, i _{K, bc}, i _{K, bs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place half-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place all-wave fourier algorithm;

By formula:

Calculate the differential current first-harmonic value of all-wave fourier algorithm, in the formula, i _{K+1, qc}, i _{K+1, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k+1 point place phase current first-harmonic in the all-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k point place phase current first-harmonic in the all-wave fourier algorithm;

If

With Ratio greater than the threshold value (scope that threshold refers to is 0.15-0.3) of magnetizing inrush current, then judge it is to shove; Otherwise be overcurrent/short circuit; Wherein, N is the sampling number of every power frequency period, gets 24; Threshold value preferred 0.2 can be distinguished magnetizing inrush current and fault current reliably.

A kind of current protection control device of realizing said method comprises power module, single-chip microcomputer, A, C phase current mutual inductor, electric quantity signal collecting module, toggle switch state input module, relay output module and tripping coil driver module; The output of described power module connects the power input of single-chip microcomputer; The output of A, C phase current mutual inductor connects the input of electric quantity signal collecting module respectively, and the output of signal acquisition module connects the acquired signal input of single-chip microcomputer after the A/D conversion; The output of toggle switch state input module connects the input of single-chip microcomputer; The output of single-chip microcomputer connects the input of relay output module, and the output of relay output module connects the control end of tripping coil driver module, and the power end of tripping coil driver module is connected to the output of A, C instrument transformer; The output of tripping coil driver module connects outside tripping coil.

Described electric quantity signal collecting module comprises two current transformer CT1, CT2, their input connects the output of A, C phase current mutual inductor respectively, and the output signal of two current transformers is imported the acquired signal input of single-chip microcomputer respectively again into through the A/D conversion after adjustable resistance, the conditioning of group capacitor filter circuit.Described A, C phase current mutual inductor output current in current transformer CT1 and CT2 sampling back and the output that is connected to the input that is connected micro-transformer of current CT3 together, current transformer CT3 connect input through power module.Described toggle switch state input module is 10 road toggle switchs.

Described tripping coil driver module comprises booster circuit, storage capacitor and rectifier bridge, and booster circuit and energy storage capacitor in series are the storage capacitor charging; Storage capacitor is with rectifier bridge and be linked together the tripping coil that is connected the control device outside, and the control tripping coil is threaded off.

Described single-chip microcomputer is the new C8051F series monolithic C8051F206 that U.S. Silicon Laboratories company releases, and its pin 9,10 connects corresponding crystal oscillating circuit, and frequency is 16MHz; The RESET input of single-chip microcomputer also connects reset circuit, and the output of single-chip microcomputer also connects the display module that LED forms.

Described clock module is by I ²C bus interface real-time timepiece chip DS1307 and+button cell of 3V forms, and selects the 32.768kHz crystal oscillator for use.The concrete mode of connection requires wiring according to the DS1307 operation instructions.

Compared with prior art, beneficial effect of the present invention is as follows:

Adopt the high-performance single-chip microcomputer, can directly apply to the 24kV line-breaker of only installing A, C biphase current instrument transformer,, escape the current protection control device that shoves as cutting off overcurrent, short circuit line.Its power supply is directly taken from the line current instrument transformer, does not need extra equipment such as voltage transformer.

In the electric quantity signal context of detection, it comprises electromagnetic interference suppression circuit, has very high reliability; And exempt to adjust, to Current Transformer Secondary side electric current identification range between 3A-50A.

Aspect the guard time cooperation, its overcurrent delay time has that 4 grades of 16 grades of optional, quick-break electric current multiples are optional, 4 grades of quick-break delay times are optional, 4 grades of combined floodgate delay times are optional, can fully satisfy the needs of actual motion.

Aspect the separating brake control of line-breaker, what its tripping coil drive circuit adopted is the mode that charging capacitor and line current provide electric current simultaneously; Because charging capacitor has been arranged, the power requirement of current transformer is little on the circuit, and 5VA gets final product, like this size of current transformer can do smaller, precision also can improve, and makes its easier installation and use.

The online identification aspect of passing by stream, short circuit and shoving, it adopts by calculating current effective value and starts the fault distinguishing program, comes identification circuit overcurrent, short-circuit condition and shoves based on the magnetizing inrush current identification new method of differential current wave character.Promptly add time-delay when powering on suddenly at device, what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves; Surpass setting value if after stable operation, calculate current effective value, utilize the magnetizing inrush current identification new method of differential current wave character to come identification circuit overcurrent, short circuit or shove,, and circuit at the corresponding levels is implemented protection with shoving of avoiding that subordinate's circuit occurs.

Since used clock module, this clock chip can be independent of CPU work, accurate timing, and the month to date error is generally less than 10s.The warning of fault and record are all needed accurate record to the time, to make things convenient for fault inquiry.

Relay output module has adopted light lotus root device isolation, and stability improves greatly, and the cut-offfing of relay is to be determined by cut-offfing of light lotus root device.

Description of drawings

Fig. 1 is apparatus of the present invention circuit theory diagrams;

Fig. 2 is apparatus of the present invention front view;

Fig. 3 is apparatus of the present invention power circuit principle figure;

Fig. 4 is apparatus of the present invention reset circuit schematic diagram;

Fig. 5 is that A in apparatus of the present invention, C biphase current are gathered measuring principle figure;

Fig. 6 is the input of switching value input toggle switch state, an one-chip computer module schematic diagram in apparatus of the present invention;

Fig. 7 is apparatus of the present invention relay output module, LED displaying principle figure;

Fig. 8 is a tripping coil drive circuit schematic diagram in apparatus of the present invention;

Fig. 9 clock circuit schematic diagram;

Figure 10 is a Single Chip Microcomputer (SCM) program flow chart in apparatus of the present invention.

A is that 10 road toggle switchs, B are that A phase adjustable resistance, C are that C phase adjustable resistance, D are LED lamps, 1～5th among Fig. 2, aerial lug

Embodiment

The invention will be further described below in conjunction with accompanying drawing and embodiment.

A kind of current protection control method comprises step: time-delay sampling when powering on suddenly, and what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves; After stable operation, calculate current effective value and surpass setting value; If do not surpass setting value, then resampling; If effective value surpasses setting value, judge that then electric current shoves or overcurrent/short circuit in the circuit; If shove then resampling; If the protection action is then made in overcurrent/short circuit.Setting value determines that by the electric current of minitype CT 1 secondary side general range is 5A-30A.In the present embodiment, setting value is 5A.

Current effective value is by formula in the described decision circuitry:

Draw; In the formula, the sampling number of N-discrete sampling; i _iThe instantaneous value of-sampling instant electric current.Described sampling number 〉=20, the sampling period is 20ms.In the present embodiment, preferably sampling number is 24.Determining of sampling period because power frequency is 50Hz in the available circuit.

By formula:

Calculate the difference of k point place's half-wave fourier algorithm and all-wave fourier algorithm, in the formula, i _{K, bc}, i _{K, bs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place half-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place all-wave fourier algorithm;

By formula: Calculate the differential current first-harmonic value of all-wave fourier algorithm, in the formula, i _{K+1, qc}, i _{K+1, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k+1 point place phase current first-harmonic in the all-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k point place phase current first-harmonic in the all-wave fourier algorithm;

If

With

Ratio greater than the threshold value of magnetizing inrush current, then judge it is to shove; Otherwise be overcurrent/short circuit; Wherein, N is the sampling number of every power frequency period, gets 24; Threshold value gets 0.2 can distinguish magnetizing inrush current and fault current reliably.

A kind of current protection control device of realizing said method comprises power module, single-chip microcomputer, A, C phase current mutual inductor, electric quantity signal collecting module, toggle switch state input module, relay output module and tripping coil driver module; The output of described power module connects the power input of single-chip microcomputer; The output of A, C phase current mutual inductor connects the input of electric quantity signal collecting module respectively, and the output of signal acquisition module connects the acquired signal input of single-chip microcomputer after the A/D conversion; The output of toggle switch state input module connects the input of single-chip microcomputer; The output of single-chip microcomputer connects the input of relay output module, and the output of relay output module connects the control end of tripping coil driver module, and the power end of tripping coil driver module is connected to the output of A, C instrument transformer; The output of tripping coil driver module connects outside tripping coil.

Described electric quantity signal collecting module comprises two current transformer CT1, CT2, their input connects the output of A, C phase current mutual inductor respectively, and the output signal of two current transformers is imported the acquired signal input of single-chip microcomputer respectively again into through the A/D conversion after adjustable resistance, the conditioning of group capacitor filter circuit.Described A, C phase current mutual inductor output current in current transformer CT1 and CT2 sampling back and the output that is connected to the input that is connected micro-transformer of current CT3 together, current transformer CT3 connect input through power module.Described toggle switch state input module is 10 road toggle switchs.

Described tripping coil driver module comprises booster circuit, storage capacitor and rectifier bridge, and booster circuit and energy storage capacitor in series are the storage capacitor charging; Storage capacitor is with rectifier bridge and be linked together the tripping coil that is connected the control device outside, and the control tripping coil is threaded off.

Described single-chip microcomputer is the new C8051F series monolithic C8051F206 that U.S. Silicon Laboratories company releases, and its pin 9,10 connects corresponding crystal oscillating circuit, and frequency is 16MHz; The RESET input of single-chip microcomputer also connects reset circuit, and the output of single-chip microcomputer also connects the display module that LED forms.

Described clock module is by I ²C bus interface real-time timepiece chip DS1307 and+button cell of 3V forms, and selects the 32.768kHz crystal oscillator for use.The concrete mode of connection requires wiring according to the DS1307 operation instructions.

Shown in Fig. 3,4, power module suppresses circuit, common mode and differential mode inhibition circuit by current transformer, full-wave rectifying circuit, voltage stabilizing circuit, transient overvoltage and forms.Circuit A, C biphase current instrument transformer output current are in micro-transformer of current sampling back and be connected to together, through inner another micro-transformer of current of controller, full-wave rectifying circuit, voltage stabilizing circuit, make alternating voltage become the little 12V direct voltage of fluctuation, promptly can be the relay power supply.Start-up circuit, serial regulating circuit, protective circuit are contained in integrated voltage stabilizing chip 7805 inside, + 12V direct voltage is become stable+5V voltage, be the power supply of devices such as amplifier, voltage stabilizing didoe Z1 with the overvoltage Limiting of circuit at certain level, protection relay coil and back level 7805 devices such as grade; Capacitor C 2 can suppress the noise that produces because of load variations, plays a part a low frequency disturbance filter.Again+5V direct voltage being become stable+3.3V voltage, is the power supply of controller inside single-chip microcomputer, and output connects 10uF electric capacity and guarantees the stability exported, and as shown in Figure 4, the voltage checking chip of Cai Yonging is the MAX708RD of PHILIPS Co. here.MAX708RD is the voltage monitoring chip of a being used for+3.3V power-supply system, and the threshold voltage that resets is+2.63V to have double loop power supply monitoring, power-fail alarm and reset function and hand-reset function.When reset button SW1 closure, system just powered on or the supply voltage of MAX708RD drop to+2.63V is once the time, low active homing output pin step-down, chip C8051F206 reliable reset.

Display module is made up of the LED display lamp, the sign of setting as setting value, promptly the user when the controller input applies the 5A electric current, regulate adjustable resistance, when light-emitting diode display became even flicker by not working, the setting value setting finished.The LED display lamp is attempted by the relay coil two ends.

As Fig. 5, shown in 6, electric quantity signal collecting module is divided into A, C two phase acquisitions, and each is by a current transformer, one road adjustable resistance, rc filter circuit, and amplifier is formed, and inserts P0.2, the P0.3 pin of single-chip microcomputer respectively.

As shown in Figure 6, toggle switch state input module adopts 10 road toggle switchs, connects P2.0, P2.1, P2.2, P2.3, P2.4, P2.5, P1.0, P1.1, P1.2, the P1.3 pin of single-chip microcomputer respectively.

As shown in Figure 7, relay output module is made up of relay, optocoupler TLP521, driving triode and protective circuit, and single-chip microcomputer output pin P1.7 is connected with the control utmost point of triode, relay two ends parallel connected in reverse phase fast diode IN4148.

As shown in Figure 8, the tripping coil driver module is made up of booster circuit, storage capacitor, rectifier bridge, connects the tripping coil of control device outside as output port.

The wiring of clock module as shown in Figure 9.

Device adopts single-chip microcomputer C8051F206 as control chip, utilizes A/D converter collection A, C biphase current in the sheet, is handled by single-chip microcomputer.Control program in this single-chip microcomputer is realized current protection control method.

The present invention adopts by calculating current effective value and starts the fault distinguishing program, comes identification circuit overcurrent, short-circuit condition and shoves based on the magnetizing inrush current identification new method of differential current wave character.When big electric current appears in circuit, may be circuit overcurrent, short circuit, also might be shoving that certain no-load transformer closes a floodgate and occurs on the circuit.Different just because of magnetizing inrush current and short circuit current waveform feature, so this paper adopts based on the magnetizing inrush current identification new method of differential current wave character and just can correctly distinguish overcurrent, the short-circuit condition of circuit when big electric current appears in circuit, escapes and shoves.

The computing formula of current effective value as shown in Equation 1.

$I=\sqrt{\frac{1}{T}{\∫}_0^T{i}^2\mathrm{dt}}...\left(1\right);$ In the formula, the instantaneous value of i-electric current; The cycle of T-electric current; The effective value of I-electric current;

It is as follows that discretization obtains the computing formula 2 of current effective value:

$I=\sqrt{\frac{1}{N}\underset{i=1}{\overset{\mathrm{<figure-callout\; id="2"\; label="N\; i\; i"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">N</figure-callout>}}{\mathrm{\&Sigma;}}}{i}_i^{}{}_2^{}}...\left(2\right);$ In the formula, the sampling number of N-discrete sampling; i _iThe instantaneous value of-sampling instant electric current; 24 points of sampling in sampling period (20ms) are deposited and are calculated after the inner ADC of process single-chip microcomputer C8051F206 is converted to digital quantity, observe calculated value and whether surpass setting value.If do not surpass, resampling also calculates, and new circulation is taken turns in beginning one; If surpass, start the recognizer that shoves.

Single-chip microcomputer need calculate the sampled signal of discrete type, supposes that the sampling number in each cycle is N, and sampling order is M=0～(N-1), formula (3) is arranged then, and (4) are as follows.

$I_{\mathrm{kM}}=\frac{4}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{i}_k\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{k\&pi;}}{N}+\frac{4i}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="i\; k\; sin"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_k\sin \frac{2\mathrm{k\&pi;}}{N}---\left(3\right)$

$I_{\mathrm{kN}}=\frac{2}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{i}_k\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{k\&pi;}}{N}+\frac{2i}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="i\; k\; sin"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_k\sin \frac{2\mathrm{k\&pi;}}{N}---\left(4\right)$

The design chooses N=24, then has formula (5)～(14) as follows.

$i_{1,\mathrm{bc}}=\frac{4}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{i}_k\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{6}[(f_0-f_{12})+0.259(f_5-f_7-{\mathrm{<figure-callout\; id="17"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{17}+f_{19})+---\left(5\right)$

$0.5(f_4-f_8-{\mathrm{<figure-callout\; id="16"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{16}+f_{20})+0.707(f_3-f_9-{\mathrm{<figure-callout\; id="15"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{15}+f_{21})+$

$0.866(f_2-f_{10}-{\mathrm{<figure-callout\; id="14"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{14}+f_{22})+0.966(f_1-f_{11}-{\mathrm{<figure-callout\; id="13"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{13}+f_{23})]$

$i_{1,\mathrm{bs}}=\frac{4i}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="i\; k\; sin"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_k\sin \frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{6}[(f_6-f_{18})+0.259(f_1+f_{11}-f_{13}-f_{23})+---\left(6\right)$

$0.5({\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_2+f_{10}-f_{14}-f_{22})+0.707({\mathrm{<figure-callout\; id="3"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700014H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_3+f_9-f_{15}-f_{21})+$

$0.866({\mathrm{<figure-callout\; id="4"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_4+f_8-f_{16}-f_{20})+0.969({\mathrm{<figure-callout\; id="5"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700012H3.png"\; state="\{\{state\}\}">f</figure-callout>}}_5+f_7-f_{17}-f_{19})]$

$I_{1M}=\sqrt{i_{1,\mathrm{<figure-callout\; id="2"\; label="bc"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">bc</figure-callout>}}^2+i_{1,\mathrm{bs}}^2}---\left(7\right)$

$i_{1,\mathrm{qc}}=\frac{2}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{i}_k\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{12}[(f_0-f_{12})+0.259(f_5-f_7-{\mathrm{<figure-callout\; id="17"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{17}+f_{19})+---\left(8\right)$

$0.5(f_4-f_8-{\mathrm{<figure-callout\; id="16"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{16}+f_{20})+0.707(f_3-f_9-{\mathrm{<figure-callout\; id="15"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{15}+f_{21})+$

$0.866(f_2-f_{10}-{\mathrm{<figure-callout\; id="14"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{14}+f_{22})+0.966(f_1-f_{11}-{\mathrm{<figure-callout\; id="13"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{13}+f_{23})]$

$i_{1,\mathrm{qs}}=\frac{2i}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="i\; k\; sin"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_k\sin \frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{12}[(f_6-f_{18})+0.259(f_1+f_{11}-f_{13}-f_{23})+---\left(9\right)$

$0.5({\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_2+f_{10}-f_{14}-f_{22})+0.707({\mathrm{<figure-callout\; id="3"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700014H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_3+f_9-f_{15}-f_{21})+$

$0.866({\mathrm{<figure-callout\; id="4"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_4+f_8-f_{16}-f_{20})+0.969({\mathrm{<figure-callout\; id="5"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700012H3.png"\; state="\{\{state\}\}">f</figure-callout>}}_5+f_7-f_{17}-f_{19})]$

$I_{2M}=\sqrt{i_{1,\mathrm{<figure-callout\; id="2"\; label="qc"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">qc</figure-callout>}}^2+i_{1,\mathrm{qs}}^2}---\left(10\right)$

$I_M=I_{1M}-I_{2M}---\left(11\right)$

$i_{2,\mathrm{qc}}=\frac{2}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{i}_k\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{12}[(f_0-f_{12})+0.259(f_5-f_7-{\mathrm{<figure-callout\; id="17"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{17}+f_{19})+---\left(12\right)$

$0.5(f_4-f_8-{\mathrm{<figure-callout\; id="16"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{16}+f_{20})+0.707(f_3-f_9-{\mathrm{<figure-callout\; id="15"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{15}+f_{21})+$

$0.866(f_2-f_{10}-{\mathrm{<figure-callout\; id="14"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{14}+f_{22})+0.966(f_1-f_{11}-{\mathrm{<figure-callout\; id="13"\; label="f"\; filenames="C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_{13}+f_{23})]$

$i_{2,\mathrm{qs}}=\frac{2i}{N}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{<figure-callout\; id="2"\; label="i\; k\; sin"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_k\sin \frac{2\mathrm{k\&pi;}}{N}$

$=\frac{1}{12}[(f_6-f_{18})+0.259(f_1+f_{11}-f_{13}-f_{23})+---\left(13\right)$

$0.5({\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_2+f_{10}-f_{14}-f_{22})+0.707({\mathrm{<figure-callout\; id="3"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700014H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_3+f_9-f_{15}-f_{21})+$

$0.866({\mathrm{<figure-callout\; id="4"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">f</figure-callout>}}_4+f_8-f_{16}-f_{20})+0.969({\mathrm{<figure-callout\; id="5"\; label="f"\; filenames="C2008100240700011H2.png,C2008100240700012H3.png"\; state="\{\{state\}\}">f</figure-callout>}}_5+f_7-f_{17}-f_{19})]$

$I_N=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_{2,\mathrm{<figure-callout\; id="2"\; label="qc"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">qc</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">i</figure-callout>}}_{2,\mathrm{qs}}^2}-\sqrt{i_{1,\mathrm{<figure-callout\; id="2"\; label="qc"\; filenames="C2008100240700011H2.png,C2008100240700013H1.png"\; state="\{\{state\}\}">qc</figure-callout>}}^2+i_{1,\mathrm{qs}}^2}---\left(14\right)$

I _1M, I _2MBe respectively the sampling calculated value of half-wave fourier algorithm and all-wave fourier algorithm, I _MDifference for the sampled value of half-wave fourier algorithm and all-wave fourier algorithm; I _NThe differential current first-harmonic value that calculates for the all-wave fourier algorithm.

The operation equation foundation: utilize the magnetizing inrush current identification new method based on the differential current wave character, the overcurrent of identification circuit, short-circuit condition escape and shove.

The corresponding action equation is formula 15 therewith, and is as follows:

$\frac{\underset{k=1}{\overset{N/2}{\mathrm{\&Sigma;}}}{I}_M}{\underset{k=1}{\overset{N/2}{\mathrm{\&Sigma;}}}{I}_N}>K_{\mathrm{dz}}---\left(15\right);$ In the formula, K _DzThe threshold value of-the magnetizing inrush current adjusted gets 0.2.Above-mentioned formula and find the solution all and can realize by the program in the single-chip microcomputer.

Program circuit as shown in figure 10, concrete steps are:

(1) initialization;

(2) combined floodgate time-delay (adjustable);

(3) gather A, C biphase current and judge whether current effective value surpasses setting value;

(4) not, then resampling returns step 3; Be, then the phase current that surpasses setting value carried out discrete Fourier and decompose, obtain the difference of sampled value of half-wave fourier algorithm and all-wave fourier algorithm and the ratio of the differential current first-harmonic value that the all-wave fourier algorithm calculates.If ratio surpasses the threshold value of magnetizing inrush current, then thinking has the unexpected idle-loaded switching-on of transformer in the circuit, does not have overcurrent, short trouble, also returns step 3.If ratio does not surpass the threshold value of magnetizing inrush current, then in the delay time that is provided with by the switching value input, judge whether circuit exists overcurrent, short-circuit condition continuously; If not overcurrent, the short circuit of continuation, return step 3, if the overcurrent of continuation, short circuit, then control circuit breaker open operation.

(5) finish.

The internal structure of device and outside connected mode are as shown in Figure 1.Device has 5 outside leads, and wherein 3 connect A, C phase current mutual inductor, and the common port of current transformer connects casing, inserts the earth; Other 2 connect tripping coil, the control breaker open operation.In the frame of broken lines is the internal structure of device, and connected mode is that lead connects.

The front view of device as shown in Figure 2.By adjusting, setting value can be adjusted into 5A to adjustable resistance B, C.Control method is as follows: will install with the A phase current mutual inductor and connect, and the instrument transformer output current is adjusted into 5A, and regulate adjustable resistance B against the direction of arrow among the figure then.When LED lamp D becomes even flicker by not working, A phase setting value is that adjusted is 5A.C phase setting value method of adjustment is with the method for adjustment of A phase.

After the setting value adjustment finishes, carry out the setting of guard time.1～4 the tunnel of 10 road toggle switch A is provided with the overcurrent delay time among Fig. 2, and 16 kinds of selections are arranged, and the concrete time can be fixing in the Single Chip Microcomputer (SCM) program the inside as required; 5～6 the tunnel are provided with the quick-break multiple, and promptly the threshold value of short circuit current can have 4 kinds of selections; 7～8 the tunnel are provided with the quick-break delay time, and 4 kinds of selections are arranged; The setting that 9～10 close a floodgate hides and shove and delay time has four kinds of selections.Like this, the actual act time of circuit breaker is the summation of combined floodgate time-delay and overcurrent, quick-break delay time.For example, the overcurrent delay time is set to 1000ms, and the combined floodgate delay time is set to 800ms, and then circuit breaker is 1000ms+800ms=1800ms total operate time.

After above-mentioned steps all finishes, will install and connect with line-breaker and fixing.Line 1～3 connects current transformer among Fig. 2, and 4～5 connect tripping coil.When line-breaker powered on suddenly, device started the internal delay time program, escaped shoving of this moment; After circuit stable operation, if occur shoving, device can identify it according to algorithm, can not make the circuit breaker misoperation; Only be under overcurrent, the short-circuit condition at circuit, device is just controlled its switching value output circuit, makes it connect the tripping coil drive circuit.Tripping coil get electric after, impact the snap close link of breaker operation mechanism, remove its deadlock state, breaker open operation.

Structurally, device adopts inserter structure, independent closed cell cabinet, and good airproof performance, anti-interference, firm reliable, the anti-vibration ability is strong.

Claims (3)

1, current protection control method in a kind of 24kV vacuum circuit-breaker comprises step:

1) time-delay sampling when powering on suddenly, what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves;

2) after stable operation, calculate current effective value in the circuit,

3) if effective value does not surpass setting value, then resampling; If effective value surpasses setting value, judge that then electric current shoves or overcurrent/short circuit in the circuit; If shove then resampling, if the protection action is then made in overcurrent/short circuit;

Described step 2) in, current effective value is by formula in the circuit:

Draw, in the formula, the sampling number of the every power frequency period of N-; i _iThe instantaneous value of-sampling instant electric current;

It is characterized in that in the described step 3), described setting value is got scope 5A-30A; By formula:

Calculate the difference of k point place's half-wave fourier algorithm and all-wave fourier algorithm, in the formula, i _{K, bc}, i _{K, bs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place half-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of phase current in the k point place all-wave fourier algorithm;

By formula:

Calculate the differential current first-harmonic value of all-wave fourier algorithm, in the formula, i _{K+1, qc}, i _{K+1, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k+1 point place phase current first-harmonic in the all-wave fourier algorithm; i _{K, qc}, i _{K, qs}Be respectively the cosine coefficient and the sinusoidal coefficient of k point place phase current first-harmonic in the all-wave fourier algorithm;

If

With

Ratio greater than the threshold value of magnetizing inrush current, the scope of threshold value is 0.15-0.3, then judges it is to shove; Otherwise be overcurrent/short circuit.

2, current protection control method in the 24kV vacuum circuit-breaker according to claim 1 is characterized in that described sampling number 〉=20, and the sampling period is 20ms.

3, current protection control method in the 24kV vacuum circuit-breaker according to claim 1 and 2 is characterized in that described sampling number N is 24; Threshold value is 0.2, can distinguish magnetizing inrush current and fault current reliably.

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